This invention relates to loose-leaf binders or notebooks and more particularly, to an improved ring mechanism for retaining paper within the notebook.
A popular type of paper used with loose-leaf binders contains holes located near one edge of the paper. The paper can be stacked neatly and securely by inserting ring posts through the holes of the paper. These rings are commonly found in binders which also include a cover consisting of two flap portions joined by a central backing. The cover is often constructed of vinyl-covered cardboard or plastic.
The ring mechanism in the binder extends along the length of the backing on the inside of the cover and is secured thereto. The ring mechanism usually includes a pair of rails or blades nested under a resilient cover plate and two or more pairs of cooperating ring elements fixed to the blades. The blades are generally in a side-by-side relationship and are under tension because the combined width of the blades is slightly greater than the width of the plate. As a result, the ring members can be locked in either an open or shut position by applying stress to the ring members and forcing the blades to buckle either concavely or convexly beneath the cover plate.
Representative examples of prior ring assemblies showing one or more of these features are: U.S. Pat. No. 1,634,125; U.S. Pat. No. 1,815,511; U.S. Pat. No. 2,006,795; U.S. Pat. No. 2,504,355; French Pat. No. 1,201,593; German Pat. No. 687,769; and Swedish Pat. No. 181,288.
It is essential to the effective operation of the binder that the ring elements, each of which is independently affixed to a blade, always meet exactly at a juncture above the plate. Otherwise, paper can slip between the ring elements and out of the binder. The most common way for the ring elements to become disjointed is for the two blades to slide longitudinally with respect to each other. This may occur during normal use when substantial force is needed to close and separate the ring elements, or when the entire binder is dropped or undergoes unusual stress.
Some currently used ring mechanisms are constructed to reduce the possibility of the ring elements becoming disjointed by inserting the ring elements through coves or holes in the plate. These coves or holes limit the lateral movement of ring elements, but, because the coves or holes are necessarily larger than the diameter or thickness of the ring elements, there is still some leeway for the ring elements to move laterally. Often, even this slight leeway is sufficient to allow the ring elements to become disjointed after use because one or both of the blades have slid longitudinally to the extent permitted by the coves or holes. Reducing the size of the coves or holes increases the chances that the ring elements will not extend through the plate with sufficient space for smooth operation or, given the normal imprecision in machining that occurs, that the ring elements will even fit through the plate.
Accordingly, an object of the invention is to provide a new and improved ring mechanism which resists longitudinal displacement of the blades and insures a proper connection and meeting of the ring elements. A further object is to produce a stronger and more reliable base plate for the ring mechanism. Yet another object is to provide a more secure loose-leaf binder which is not easily damaged or disabled by shocks to the ring mechanism.